Bridges are typically designed and constructed with a limited lifetime in mind. However, such lifetime objectives can be difficult to achieve due to unforeseeable environmental damage, higher than expected traffic loads, or planning and construction errors.
These factors lead to a reduced safety classification (e.g. the Structural Evaluation Scale), which often means that speed or weight limits must be put on the bridge to ensure safety, or in the worst case requires extensive repair or a total rebuild.
Current bridge inspection technologies are typically based on strain gauges, accelerometers, or distance meters. Such instruments need to be mounted on the bridge which can be very time consuming and costly, depending on accessibility to the bridge.
Dantec’s Digital Image Correlation (DIC) technology has successfully been applied to evaluation of large structures such as bridges. The technology is based on recognition of speckle patterns naturally occurring on the object and allows measuring displacements and deformations of the object under inspection with sub-millimetre accuracy.